An approach to the dynamic modelling of manufacturing systems

Abstract

Because of their complexity manufacturing systems are di cult to model. However, modelling is very often required in order to study the behaviour of the system. In this paper an approach is described, where an analogy is drawn between the behaviour of a manufacturing and a mechanical system. Manufacturing systems have to respond to a dynamic demand, namely, a demand that changes over time. Flexibility of a manufacturing system can be thought of as the ability and the rapidness with which the system responds to the dynamic demand. This resembles the behaviour of a mechanical system under the excitation of a force that changes over time. The paper attempts to establish a modelling method based on this analogy and uses this method in the study of a real industrial system.

Flexibility evaluation: A toolbox approach

“…(2006), where real or near real time monitoring of the data related to various manufacturing parameters, gathered during the operation of a production system, are incorporated in order to provide eventually the flexibility performance of a production system. This approach has been motivated by the well-established dynamic behaviour analogy between a mechanical and a manufacturing system (Chryssolouris 1996, Chryssolouris et al 1998). …”

“…Bateman et al (1999) have extended the 'sensitivity to change' approach while Alexopoulos et al (2005a) have applied this approach to a real case study of the commercial refrigerators production industry. Chryssolouris et al (1998) have proposed a measure of flexibility, based on the calculation of the transfer function of the manufacturing system. The transfer function describes the way a manufacturing system responds to changes in the input, i.e.…”

Quantifying the flexibility of a manufacturing system by applying the transfer function

“…It must be noted that at Ω i the phase angle changes sign and thus a criterion for the identification of Ω i can be established (see Chryssolouris et al (1998)). FLEXIMAC is then calculated as an average value of the ten largest Q i .…”

“…Moreover, Chryssolouris et al (1998) have proposed a measure of flexibility, based on the calculation of the transfer function of the manufacturing system. The 'transfer function' describes the way a manufacturing system responds to changes in the inputi.e., to various orders of different products and to different volumes, in the same manner as the transfer function characterizes a simple mechanical system, which responds under the excitation of a force vibrating over time.…”

Oscillator analogy for modelling the manufacturing systems dynamics

“…In Chryssolouris et al (1998) they have used the mechanical analogy concept to assess the flexibility of a manufacturing system. Their approach calculates the damping factor of a manufacturing system, from the eigenvalues of the transfer function in the frequency domain.…”